Environ. Sci. Technol. 2008, 42, 2496–2502
Physical and Chemical Characterization of Residential Oil Boiler Emissions M I C H A E L D . H A Y S , * ,† L E E B E C K , † PAMELA BARFIELD,† RICHARD J. LAVRICH,† YUANJI DONG,‡ AND RANDY L. VANDER WAL§ National Risk Management Research Laboratory, United States Environmental Protection Agency, Research Triangle Park, North Carolina 27711, The Universities Space Research Association (USRA), Glenn Research Center, National Aeronautics and Space Administration (NASA), Cleveland, Ohio 44135, and ARCADIS, Research Triangle Park, North Carolina 27711
Received June 29, 2007. Revised manuscript received November 16, 2007. Accepted January 7, 2008.
The toxicity of emissions from the combustion of home heating oil coupled with the regional proximity and seasonal use of residential oil boilers (ROB) is an important public health concern. Yet scant physical and chemical information about the emissions from this source is available for climate and air quality modeling and for improving our understanding of aerosolrelated human health effects. The gas- and particle-phase emissions from an active ROB firing distillate fuel oil (commonly known as diesel fuel) were evaluated to address this deficiency. Ion chromatography of impactor samples showed that the ultrafine ROB aerosol emissions were ∼45% (w/w) sulfate. Gas chromatography–mass spectrometry detected various n-alkanes at trace levels, sometimes in accumulation mode particles, and out of phase with the size distributions of aerosol mass and sulfate. The carbonaceous matter in the ROB aerosol was primarily light-adsorbing elemental carbon. Gas chromatography-atomic emission spectroscopy measured a previously unrecognized organosulfur compound group in the ROB aerosol emissions. High-resolution transmission electron microscopy of ROB soot indicated the presence of a highly ordered primary particle nanostructure embedded in larger aggregates. Organic gas emissions were measured using EPA Methods TO-15 and TO-11A. The ROB emitted volatile oxygenates (8 mg/(kg of oil burned)) and olefins (5 mg/(kg of oil burned)) mostly unrelated to the base fuel composition. In the final analysis, the ROB tested was a source of numerous hazardous air pollutants as defined in the Clean Air Act Amendments. Approximations conducted using emissions data from the ROB tests show relatively low contributions to a regionallevel anthropogenic emissions inventory for volitile organic compounds, PM2.5, and SO2 mass.
* Corresponding author phone: 919-541-3984; fax: 919-685-3346; e-mail:
[email protected]. † United States Environmental Protection Agency. ‡ ARCADIS. § NASA. 2496
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Introduction The United States uses approximately 25 billion liters of distillate fuel oil (diesel) in combustion devices for residential heating, accounting for more than one-tenth of the total yearly U.S. consumption of this fuel (1). Residential oil boilers (ROBs) are clustered in densely populated urban centers particularly in the Northeastern U.S. Their use is concentrated in the winter season, and their emissions are toxic, resulting in considerable public health concern (2). The toxicity of ROB emissions is a function of the chemical composition of the aerosol matter and organic gas mixture and possibly particle size (3, 4). Determination of these properties is important for surmising how and why biological response to ROB emissions may vary. Fossil fuel combustion is a significant source of aerosol sulfates. Residential oil boilers may emerge as a notable source of gas- and particle-phase sulfur, considering that the recent federal rules lowering sulfur content in on- and off-road diesel fuels do not yet apply to home heating oils (5). There is scant information about the composition of modern ROB emissions. Of the studies available, most were conducted without dilution sampling or using burners that are now obsolete (see refs 6 and 7 and references therein). These studies contain virtually no information about the chemical attributes of particles by size or the physical properties of ultrafines, despite having measured metal, polycyclic aromatic hydrocarbon, gaseous hydrocarbon, SO2, NOx, particle mass, and sulfate emissions from the ROB source. By identifying multiring aromatic, biphenyl, thiophenic, and various oxygenated substances in solvent-fractionated gas- and condensed-phase ROB emissions, Leary et al. (7) sharpened the description of the organic mixture. However, quantitative phase partitioning measurements and data for oxygenated organic gases are still unavailable for this source. Many organic gases are PM2.5 precursors. Source contributions of organic gases to the atmosphere are required for approximating regional to global atmospheric carbon budgets important for oxidant, toxics, and air quality modeling. Recently, much of the extensive chemical characterization of emissions has been limited to heavy oil combustion in industrialsor commercial-scale and fire-tube-package boilers (8, 9). While noteworthy, these investigations are not expected to characterize the emissions from a residential boiler firing distillate oil. Size distribution and chemical composition of PM emissions differ with oil-firing technique, boiler type, fuel composition and grade, operating conditions, and other factors (9). The objective of this study was to obtain improved or missing quantitative chemical information for the ROB emissions source. To accomplish this objective, dilution testing of the emissions from a flame retention-head ROB firing distillate oil was conducted. Collected samples were analyzed using various techniques. Aerosol particle mass and size distributions were determined gravimetrically using a low-pressure impactor. The impactor samples were subject to gas chromatography–mass spectrometry (GC-MS) and ion chromatography (IC) analyses in an effort to measure the sulfate and organic marker composition by particle size. Inductively coupled plasma-mass spectrometry (ICP-MS) determined the elemental composition and toxic heavy metal concentrations in the ROB particles. The presence of organosulfur compounds in the bulk particles is established for the first time using a gas chromatograph coupled to an atomic emission detector. Unpublished evidence found recently in our laboratory suggests that particle nanostructure may 10.1021/es071598e CCC: $40.75
2008 American Chemical Society
Published on Web 02/27/2008
mediate elemental carbon particle uptake by lung epithelial cells and alveolar macrophages. It may also be of value to source-receptor research as the nanostructure is specific to the combustion process and fuel composition (10). The PM morphology and nanostructure were investigated by highresolution transmission electron microscopy. Finally, aldehyde and ketone and non-methane hydrocarbon gas emissions from the ROB were measured and reported.
Experimental Section Residential Oil Boiler. The ROB was located in a research test facility operated by Brookhaven National Laboratory. The boiler (Weil-McLain model SGO-5W; combustion efficiency ) 85.0) had a heating capacity of 185 MJ/h. Its firebox was surrounded by a five-section, 71 L water jacket, and the unit was equipped with a circulating pump to move liquid water through the heating system. The flame retention-head burner (Beckett model AFG) was rated for up to 5.7 L/h of No. 2 fuel oil and was designed for natural draft firing. The boiler technology tested is representative of that found in the Northeastern U.S., where these boilers are predominantly used for residential space heating in the wintertime. The composition of the No.2 fuel oil used in this study is as follows: C, 84.81; O, 2.35; H, 12.50; N, 2200 °C), and lean flame (air:fuel ratio ) 17.1:1 or ∼3% excess oxygen in the flue gas) the ROB burner produces probably inhibits the formation of coarse cenospheres, and the semivolatile organic condensates needed for further particle growth. Methods of air-fuel premixing and fuel atomization, stoichiometric ratios, and fuel batches and grades vary among different fossil fuel combustion sources, affecting flame characteristics and ultimately the size of the particles emitted (24). The average fine PM emission factor of 49 ( 5 mg/kg (milligram of aerosol per kilogram of fuel burned) determined for the ROB source concurs with the EPA AP-42 documented value of 57 mg/kg (25). Since 1974, PM emission factor values ranging from 12 to 513 mg/kg have been reported for various ROBs (6, 7). The tested ROB emits less fine PM per unit volume of fuel burned than oil-firing utility and industrial-scale boilers. Fine PM emission factors calculated using the Teflon filter and the DLPI gravimetric measurements agree within 2%. The speciated data acquired from the analysis scheme applied explain roughly 60% of the fine PM mass. The exact cause of the gap between the gravimetric data and sum of measured composition is unclear. However, the Q-QBT method used to determine the OC values reportedly overcorrects for the positive adsorption artifact by as much as 33% (see ref 13 and references therein). Although unlikely to have as much of an effect, the organic matter to OC ratio of 1.2 used here may also underestimate the extent of oxygenated organic matter in the ROB aerosol. Elemental Composition. Sulfur is the dominant chemical element identified in the ROB PM (12% (w/w)), Table S1 in the Supporting Information. It accounts for more than 95% (w/w) of the inorganic matter identified by ICP-MS but represents less than 1% of the S contained in the oil. Much 2498
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of the oil S is likely released as SO2 gas. Although the elemental composition of No. 2 distillate fuel oil is likely quite variable, several trace heavy metals previously detected in distillate fuel oil are observed in the ROB PM (26). They are As, Cd, Cr, Pb, Mn, Ni, and V. The metal composition accounts for less than 1% of the ROB PM mass (Table S1). However, six of the heavy metals identified in the PM are classified as air toxics and some may impair cardiovascular health (27). With the exceptions of Cd and Cr, the As, Pb, Ni, and V concentrations (Table S1 notes) in the ROB PM of this study are as much as 3 orders of magnitude less than those measured in residual fuel oil combustion PM, directly reflecting how these fuels differ compositionally (9). For this study, the GC-AED analysis shows no evidence of these metals coordinated to organic ligands. Particle Size Distribution of Sulfate. The IC analysis conducted on the heated impactor liners shows that the S in ROB PM is primarily water-soluble sulfate. Roughly halfs45% (w/w)sof the ROB fine aerosol collected in the impactor is ascribed to sulfate; IC analysis of the Teflon filter samples verifies this concentration. Moreover, if the ICP-MS determined S is assumed to be entirely sulfate, the aerosol comprises 36% (w/w) sulfate. Evident in Figure 1 (shortdashed lines) are the particle size distributions of sulfate produced using the IC results for the spent impactor liners. These single log-normal mode distributions are largely inphase with those of PM mass, showing a slightly lower average GMD of 32 nm with σ ) 2 nm. Following heating, the aqueous extraction and IC analysis of the impactor liners adequately recover sulfate. However, heating the aerosol (to 300 °C) may decompose and volatilize certain water-soluble salt compounds of interest [e.g., ammonium nitrate (bp 210 °C)]. Although NH4+ measured on the Teflon filters is above minimum quantification limits (0.3 ppm) for a single test day only, it is consistently below IC detection limits on the spent liners. Loss of nitrogenbearing ions may be a consequence of heating the aerosols. On the Teflon filter and liner samples, the Mg and Ca cations and NO3- and NO2- are below their 0.2 and 0.3 ppm detection limits, respectively. Organic and Elemental Carbon. The background- and artifact-corrected carbonaceous component of the ROB aerosol varies between 4 and 8% (w/w); the average emissions rate of carbon in ROB particles is 2.7 ( 0.7 mg/kg. Aerosol EC is a factor of 2 greater than OC. Primary aerosols released from oil combustion normally contain more EC than OC (28). Past studies report significantly higher fractional aerosol carbon contributions of 35 and 53% (w/w) for institutionalscale boilers firing distillate and residual oil, respectively (23, 29). The residual oil boiler was operating under peak demand, which may explain its carbon-enriched particle emissions. The carbon particle emissions from the distillate oil boiler were not artifact corrected, and the 29% soot they contained suggests insufficient oxygen during firing. The nature of primary OC ascribed to the ROB aerosol in this work is inferred from comparing manually integrated peaks in the TOT thermograms obtained for the Qf and Qb filter set. Using this analysis, only OC evolving from the filter at temperatures higher than ∼600 °C could be ascribed unambiguously to the particle phase. The Qf to Qb carbon ratio is 1.3. The possibility of the ROB aerosol particles being without semivolatile organic matter is further investigated by considering the likeness of individual SVOCs in the GCMS and GC-AED chromatograms of the Qf and Qb extracts. GC-MS Analysis of Quartz Filters. With the exception of a few unidentified peaks unique to the Qf, the TE-GC-MS chromatograms in Figure 2 reveal similar organic matter composition for Qf and Qb. Cumulatively, the results suggest that as collected the ROB particles mostly lack SVOCs, which instead favor the gas state due presumably to the high dilution
FIGURE 2. TE-GC-MS total ion chromatograms of the Qf (black) and Qb (blue) filters. The figure inset identifies the longer chain n-alkane molecules observed in the gas phase. air to organic aerosol ratio. The organic aerosol concentration range in the exhaust is 2–9 µg/m3, which closely mimics what is expected when source emissions become fully diluted in the atmosphere (30). Additionally, less volatile, late eluting organic compounds in the ROB emissions occur in the gas phase (see figure inset). The elevated levels of SVOCs captured on the Qb between 20 and 27 min are unchanged upon normalizing the chromatogram responses to internal standards. The difference between Qf and Qb may represent the artifact overcorrection for the Q-QBT method. Indeed, the relatively efficient volatilization of SVOCs from the front Teflon filter (referred to as negative artifact) is probably measured by the Qb only. Close examination of Figure 2 shows that more than 70% of the chromatogram area representing SVOC-eluting mass remains unresolved. Fewer than 50 of the nearly 200 peaks resolved are identified with confidence when searching an MS library using a pattern recognition algorithm. Search criteria and tentative peak assignments for organic compounds on the Qf are given in Figure S1 of the Supporting Information. Concerning the organic compound classes in fine aerosols normally targeted for analysis, only the C14-C24 n-alkanes and a few organic acids are detected on the Qf at levels above those in the Qb. Their particle-phase emission factors are estimated from the GC-MS-analyzed filter composites. After correcting for background, the n-alkane emission factors are minor (x e 10 µg/kg; Table S2 in the Supporting Information). Particle Size Distribution of the n-Alkanes. TE-GC-MS analysis identified the n-alkanes in the ROB aerosol particles collected on the individual impactor stage liners. They are seldom measured above their estimated quantification limits (EQL) of 0.2–6 ng, challenging our efforts to produce consistent particle size data for organic compounds. There is a single day of source testing for which the n-alkane concentrations either closely approach or meet the EQLs. TE-GC-MS-determined n-alkane emissions data for that day are presented to expand our understanding of the sizeresolved trace n-alkane chemistry for the ROB source. Figure 3 exhibits the size distributions of the trace n-alkanes in the ROB particle emissions. The n-alkane distributions are bimodal over the ultrafine and accumulation modes (aerodynamic diameters of e0.1 and e1 µm, respectively); although, the n-alkanes are also observed in ROB particles greater than 1 µm. The carbon preference index (CPI) as defined in Simoneit (31) ranges from 0.7 to 1.1 relating reciprocally (but erratically) to particle size. Marked changes in the positions of distribution maxima from C21 to C22 (for the smaller size mode peak) and from C24 to C25 (for the larger size mode peak) are visible. There is evidence of a
FIGURE 3. Size distributions of the trace n-alkanes (colored short dashed lines) in the residential oil boiler emissions superimposed against the PM mass (solid line) and sulfate ion (long dashed line) distributions. relationship between the position of each distribution mode peak and the n-alkane chain length. Longer straight chain hydrocarbons preferentially segregate to larger sized particles. The fact that aliphatics in controlled flames are observed contributing to soot mass growth rather than to nucleation may explain this behavior (24). Compared with the PM mass and sulfate ion distributions, the n-alkanes appear in larger particlesswith n-C20 and n-C21 as the only possible exceptions. The combustion process, dilution setting, and fuel composition modulate the particle size based emissions across different organic chemical classes. For example, the contrast in trends observed for the n-alkanes released from the ROB and for polycyclic aromatic hydrocarbons (PAHs) emitted from biomass burning is noted (18, 32). Variable load and combustion conditions for the same diesel engine also change the particle size based emissions of individual hopane and sterane molecules (33). Particle size distributions of organic compounds will require further study to determine their sensitivity to the various conditions aerosols normally experience. GC-AED Analysis Results for Sulfur. The GC-AED technique complements GC separation with element selective detection independent of molecular structure. It is used to identify the (hetero) elements in organic compounds. Of the multiple elements surveyed in the ROB aerosol (Qf) using the GC-AED, only S (using the 181 nm line) is above its 2 pg/s detection limit; see Figure 4. The partitioning of the organosulfur compounds to the aerosol phase is inferred from their absence in the Figure 4 S-AED chromatogram of the Qb. Comparatively less S in the analytical blank and the dilution VOL. 42, NO. 7, 2008 / ENVIRONMENTAL SCIENCE & TECHNOLOGY
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FIGURE 4. GC-AED sulfur element chromatograms for an analytical blank (blue), for dilution air (red), and for Qb and Qf (green and black, respectively).
FIGURE 5. Bright-field HR-TEM images of residential oil boiler soot at varying magnifications. air (Figure 4) suggests that the S on the Qf is not due to contamination. The GC-AED evidence presented is qualitative. The ROB aerosol explains less than 1% of the fuel S and much of this is sulfate; hence, the organosulfur contribution to the aerosol is likely minor. Residual oil and diesel fuels comprise organosulfur components, thiophenic S is found in residual oil combustion particles (8), but organosulfur compounds are an unrecognized fraction of carbon particle emissions from diesel fuel combustion. The crude GC-AED resolution of carbon precludes the empirical determination of organosulfur compound formulas. The GC-MS results show no evidence of the GC-AED identified organosulfur compounds, suggesting they are present in the unresolved complex mixture (UCM). Alkylated benzothiophenes are candidate petroleum UCM constituents (34). Further research is needed to measure organosulfur compounds in the ROB particle matrix, to quantify their contribution to unidentified carbon, and to determine their possible usefulness for source-receptor modeling. Soot Nanostructure. Examination of the low-magnification HR-TEM images of the ROB soot in Figure 5 show individual primary particles geometrically distinct within aggregates, indicating late-stage aggregation rather than primary particle mass growth (consistent with the lack of SVOC emissions species). The measured average primary particle size is ∼20 nm, qualitatively confirming the impactor PM size distribution GMD and perhaps reflecting the relatively uniform particle formation conditions in the ROB burner. The presence of primary particles with a high degree of ordered nanostructure did indeed set the ROB soot apart from other combustion soots (see refs 10 and 35 to compare). The large fractional EC component and lack of organic matter 2500
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found in the ROB sample may cause this source to be mistakenly neglected when developing chemical mass balance models for apportioning carbonaceous fine PM in polluted atmospheres. Hence, characterization of the relatively unreactive EC component may be used to estimate ROB contributions to atmospheric particles. The high-magnification images show carbon lamella lengths as parallel, concentric about the particle center, and regularly exceeding 10 nm. Given the intimate attachment to ROB soot with far less structure, the particles likely arise from the boiler. However, the highly ordered nanostucture is symptomatic of a formation process other than the “normal” aerosol path. The extreme temperature (>2200 °C) of the ROB flame presumably facilitates the graphitization of soot by thermally decomposing PAHs and providing the activation energy for the removal of edge-terminating atoms and cross-linking and reorienting lamella. Acetylene produced by fuel pyrolysis is considered the dominant species contributing to the ordered graphite sheets, and the acetylene concentration in the emissions is depleted relative to that of ethylene or propylene, Table S3 of the Supporting Information. Alternatively, having only observed similar structures in laboratory generated flames; it is possible they arose from a metal catalyzed process, perhaps beginning on the wall of the boiler (36). Gas-Phase ROB Emissions. Total VOC emissions from the ROB vary between 6 and 30 mg/(kg of fuel oil burned) with an average total emissions rate of 17 ( 12 mg/kg. The VOC emissions are primarily oxygenates (48% of total) and olefins (27%) unrelated to the base fuel composition; implicitly, these compounds form during combustion in the ROB. The trace paraffin and aromatic levels indicate only a minor presence of unburned fuel in the VOC emissions.
Numerous individual VOCs in the ROB emissions are designated air toxics (Table S3) and are useful to dispersion and source-receptor models (37). Moreover, the olefin double bond reacts readily with ozone to yield ozinides and the OH radicals essential to atmospheric processes. The individual gas-phase SVOCs identified and quantified in the PUFs are given in Table S3; Table S3 footnotes contain information about how these concentrations are obtained. The PUF analysis results show higher concentrations of more volatile SVOCs and confirm PAH gases in the ROB effluent. The alkyl substituted naphthalenes detected are reactants in OH radical initiated production of atmospheric dicarbonyls (38). ROB Emission Inputs to the Northeastern U. S. Nearly 80% of the 25 billion liters of home heating oil burned in the U.S. annually are consumed in the New England and Central Atlantic States. Although the equipment, fuel composition, and tests conducted may be unrepresentative of all 10 million working ROBs and how they function currently, estimates obtained using emissions data from the ROB tests show this source contributing less than 1% to the anthropogenic VOCs and PM2.5 in the Northeastern U.S. The ROB accounts for about 1% of the regional anthropogenic SO2. Despite its potentially minor contribution, the ROB is a source of numerous hazardous air pollutants and ultrafine particles and, hence, may warrant more attention in the future than it has received so far.
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Acknowledgments The authors are grateful for the assistance of Roger J. McDonald and Wai-Lin Litzke of Brookhaven National Laboratories. They also thank Drs. James J. Schauer and Martin Schafer at the University of WisconsinsMadison for providing the ICP-MS analysis results. David Profitt and Thomas Balicki of ARCADIS were central to the source testing effort.
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Supporting Information Available Emissions factor tables and a representative TE-GC-MS chromatogram of Qb, individual gas-phase organic compounds in the quartz filter, identified and ascribed to positive adsorption artifact, and further experimental information about the GC-AED method, etc. This material is available free of charge via the Internet at http://pubs.acs.org.
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Literature Cited (1) U. S. Department of Energy. Official Energy Statistics from the U.S. Government. http://www.eia.doe.gov/ (accessed September 2006). (2) Braun, A. G.; Busby, J. W. F.; Liber, H. L.; Thilly, W. G. Chemical and toxicological characterization of residential oil boiler emissions: II. Mutagenic, tumorogenic, and potential teratogenic activity. Environ. Health Perspect. 1987, 73, 253–246. (3) Hauser, R.; Godleski, J. J.; Hatch, V.; Christiani, D. C. Ultrafine particles in human lung macrophages. Arch. Environ. Health 2001, 56 (2), 150–156. (4) Oberdorster, G. Pulmonary effects of inhaled ultrafine particles. Int. Arch.Occup. Environ. Health 2001, 74 (1), 1–8. (5) U.S. Environmental Protection Agency. Direct Final Rule and Notice of Proposed Rulemaking for Amendments to Nonroad and Highway Disel Fuel Regulations; U.S. EPA: Washington, D.C., 2006. (6) Barrett, R. E.; Locklin, D. W.; Miller, S. E. Investigation of Particulate Emissions from Oil-Fired Residential Heating Units; EPA-650/2-74-026; U.S. EPA: Washington, D.C., 1974; pp 1–7.. (7) Leary, J. A.; Biemann, K.; Lafleur, A. L.; Kruzel, E. L.; Prado, G. P.; Longwell, J. P.; Peters, W. A. Chemical and toxicological characterization of residential oil boiler emissions: I. Yields and chemical characterization of extractables from combustion of No. 2 fuel oil at different Bacharach smoke numbers and firing cycles. Environ. Health Perspect. 1987, 73, 223–234. (8) Huffman, G. P.; Huggins, F. E.; Shah, N.; Huggins, R.; Linak, W. P.; Miller, C. A.; Pugmire, R. J.; Meuzelaar, H. L. C.; Mohindar, S. S.; Manivannan, A. Characterization of fine particulate matter
(22)
(23)
(24)
(25)
(26)
(27)
(28)
produced by combustion of residual fuel oil. J. Air Waste Manage. Assoc. 2000, 50, 1106–1114. Miller, C. A.; Linak, W. P.; King, C.; Wendt, J. O. L. Fine particulate emissions from heavy fuel oil combustion in a firetube package boiler. Combust. Sci. Technol. 1998, 134, 477–502. Hays, M. D.; VanderWal, R. L. Heterogeneous soot nanostructure in atmospheric and combustion source aerosols. Energy Fuels 2007, 21, 801–811. ANSI-ASHRAE, Methods of Testing for Annual Fuel Utilization Efficiency of Residential Central Furnaces and Boilers; Standard 103-1993; 1993. Hildemann, L. M.; Cass, G. R.; Markowski, G. R. A dilution stack sampler for collection of organic aerosol emissions: Design, characterization and field tests. Aerosol Sci. Technol. 1989, 10, 193–204. Subramanian, R.; Khylstov, A. K.; Cabada, J. C.; Robinson, A. Positive and negative artifacts in particulate organic carbon measurements with denuded and undenuded sampler configurations. Aerosol Sci. Technol. 2004, 38, 27–48. Dong, Y.; Hays, M. D.; Smith, N. D.; Kinsey, J. Inverting cascade impactor data for size-resolved characterization of fine particulate source emissions. J. Aerosol Sci. 2004, 35, 1497–1512. Schauer, J. J.; Lough, G. C.; Shafer, M. M.; Christensen, W. F.; Arndt, M. F.; DeMinter, J.; Park, J.-S. Characterization of Metals Emitted from Motor Vehicles; HEI: Boston, MA, 2006; Appendix A. Shafer, M. M.; Overdier, J. T.; Phillips, H.; Webb, D.; Sullivan, J. R.; Armstrong, D. E. Trace metal levels and partitioning in Wisconsin rivers. Water, Air, Soil Pollut. 1999, 110 (3–4), 273– 311. NIOSH Method 5040. In NIOSH Manual of Analytical Methods, 2nd supplement ed.; Cassinelli, M. E.; O’Connor, P. F., Eds.; National Institute of Occupational Safety and Health: Washington, D.C., 1998; Volume Supplement to DHHS (NIOSH) Publication No. 94-113. Hays, M. D.; Smith, N. D.; Kinsey, J.; Dong, Y.; Kariher, P. H. Polycyclic aromatic hydrocarbon size distributions in aerosols from appliances of residential wood combustion as measured by direct thermal desorption-GC/MS. J. Aerosol Sci. 2003, 34 (8), 1061–1084. Mazurek, M. A.; Cass, G. R.; Simoneit, B. R. T. Interpretation of high-resolution gas chromatography/mass spectrometry data acquired from atmospheric organic aerosol samples. Aerosol Sci. Technol. 1989, 10, 408–420. Hays, M. D.; Geron, C. D.; Linna, K. J.; Smith, N. D.; Schauer, J. J. Speciation of gas-phase and fine particle emissions from burning of foliar fuels. Environ. Sci. Technol. 2002, 36, 2281– 2295. Determination of Volatile Organic Compounds (VOCs) in Air Collected in Specially-Prepared Canisters and Analyzed by Gas Chromatography/Mass Spectrometry (GC/MS); Compendium Method TO-15; EPA/625/R-96/010b (NTIS PB99-172355); Center for Environmental Research Information, Office of Research and Development, U.S. Environmental Protection Agency: Cincinnati, OH, 1999. Determination of Formaldehyde in Ambient Air Using Adsorbent Cartridge Followed by High Performance Liquid Chromatography (HPLC); Compendium Method TO-11A; EPA/625/R-96/ 010b (NTIS PB99-172355); Center for Environmental Research Information, Office of Research and Development, U.S. Environmental Protection Agency: Cincinnati, OH, 1999. Bond, T. C.; Wehner, B.; Plewka, A.; Widensolhler, A.; Heintzenberg, J.; Charlson, R. J. Climate-relevant properties of primary particulate emissions from oil and natural gas combustion. Atmos. Environ. 2006, 40, 3574–3587. Oktem, B.; Tolocka, M. P.; Zhao, B.; Wang, H. V. J. M. Chemical species associated with the early stage of soot growth in a laminar premixed ethylene-oxygen-argon flame. Combust. Flame 2005, 142, 364–373. U.S. Environmental Protection Agency. Office of Air Quality Planning and StandardssClearinghouse for Emission Inventories and Emission Factors; U.S. EPA: Washington, D.C., 2001. Miller, C. A.; Ryan, J. V.; Lombardo, T. Characterization of air toxics from an oil-fired firetube boiler. J. Air Waste Manage. Assoc. 1996, 46, 742–748. Delfino, R. J.; Sioutas, C.; Malik, S. Potential role of ultrafine particles in associations between airborne particle mass and cardiovascular health. Environ. Health Perspect. 2005, 113 (8), 934–946. Bond, T. C.; Streets, D. G.; Yarber, K. F.; Nelson, S. M.; Woo, J.-H.; Klimont, Z. A technology based global inventory of black
VOL. 42, NO. 7, 2008 / ENVIRONMENTAL SCIENCE & TECHNOLOGY
9
2501
(29)
(30)
(31)
(32)
(33)
2502
and organic carbon emissions from combustion. J. Geophys Res. 2004, 109, D14203. Rogge, W. F.; Hildemann, L. M.; Mazurek, M. A.; Cass, G. R.; Simoneit, B. R. T. Sources of fine organic aerosol. 8. Boilers burning No. 2 distillate fuel oil. Environ. Sci. Technol. 1997, 31, 1997. Robinson, A. L.; Donahue, N. M.; Shrivastava, M. K.; Weitkamp, E. A.; Sage, A. M.; Grieshop, A. P.; Lane, T. E.; Pierce, J. R.; Pandis, S. N. Rethinking organic aerosols: Semivolatile emissions and photochemical aging. Science 2007, 315 (5816), 1259–1262. Simoneit, B. R. T. Organic matter of the troposphere: V. Application of molecular marker analysis to biogenic emissions into the troposphere for source reconciliations. J. Atmos. Chem. 1989, 8, 251–275. Venkataraman, C.; Negi, G.; Sardar, S. B.; Rastogi, R. Size distributions of polycyclic aromatic hydrocarbons in aerosol emissions from biofuel combustion. J. Aerosol Sci. 2002, 33, 503–518. Riddle, S. G.; Robert, M. A.; Jakober, C. A.; Hannigan, M. P.; Kleeman, M. J. Size distribution of trace organic species emitted
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(34) (35) (36) (37) (38)
from heavy-duty diesel vehicles. Environ. Sci. Technol. 2007, 41, 1962–1969. Frysinger, G. S.; Gaines, R. B.; Xu, L.; Reddy, C. M. Resolving the unresolved complex mixture in petroleum-contaminated sediments. Environ. Sci. Technol. 2003, 37, 1653–1662. Chen, Y.; Shah, N.; Huggins, F. E.; Huffman, G. P. Transmission electron microscopy investigation of ultrafine coal fly ash particles. Environ. Sci. Technol. 2005, 39, 1144–1151. Vander Wal, R. L.; Ticich, T. M.; Curtis, V. E. Directed synthesis of metal-catalyzed carbon nanofibers and graphite encapsulate metal nanoparticles. J. Phys. Chem. B 2000, 104, 11606–11611. Volckens, J.; Olson, D. A.; Hays, M. D. Carbonaceous species emitted from handheld two-stroke engines Atmos. Environ. 2007, doi:10.1016/j.atmosenv.2007.10.032 Wang, L.; Atkinson, R.; Arey, J. Dicarbonyl products of the OH radical-initiated reactions of naphthalene and the C1and C2-alkylnaphthalenes. Environ. Sci. Technol. 2007, 41, 2803–2810.
ES071598E
